How Does Observer Position Affect Rainbow Shape

An observer's position is not just important; it is fundamental to the very existence and position of the rainbow. The rainbow is not a physical object at a fixed location; it is an optical phenomenon centered entirely on the observer.

• A Rainbow is Personal: Every observer sees their own unique rainbow. The center of the rainbow's arc (the antisolar point) is defined by the line passing from the sun, through the observer's head, and extending to the sky opposite.
• Movement: If you move, your antisolar point moves with you. As a result, the entire rainbow you see moves with you. This is why you can never walk "to the end" of a rainbow; it will always appear to recede as you approach.
• Different Perspectives: Two people standing even a few feet apart will see two different rainbows. While the rainbows might look similar, they are formed by light refracting and reflecting off different sets of raindrops, and each rainbow is centered on its own observer.

In short, the observer's position does not change the fundamental shape (it's always a circle or part of one), but it completely dictates the perceived location of that circle in the sky. You are always at the geometric center of the rainbow you see.